How does the water toughening treatment process affect the final performance of high manganese steel lining plate

The unique properties of high manganese steel (such as ZGMn18Cr2) are not solely determined by its chemical composition. Its ultimate wear resistance and impact resistance are largely dependent on a key heat treatment process - water toughening treatment. The degree of standardized implementation of this process is the core link that determines whether high manganese steel lining plates can unleash their theoretical design potential. This article will objectively explain the principle of water toughening treatment, key parameter control, and its specific impact on performance.

1、 The core role and objectives of water toughening treatment

Water toughening treatment is essentially a solid solution treatment in which high manganese steel is heated to high temperature austenitization and then rapidly water quenched. Its core objectives can be summarized into two points:

Obtaining a single austenite structure: By re dissolving the network carbides (Fe, Mn) ∝ C precipitated along grain boundaries in the as cast structure into austenite and fixing them in quenching, brittle phases are eliminated, providing a high toughness foundation for the material.

Create conditions for work hardening: obtain unstable supersaturated single-phase austenite. In this state, the material is subjected to strong impact or compression during operation, and the surface austenite can quickly induce martensitic transformation and produce high-density dislocations, thereby achieving a significant increase in surface hardness (from about HB200 to above HB450), forming a wear-resistant surface layer suitable for the working conditions.

2、 Key process parameters and their performance impact

Each step of water toughening treatment has a clear impact on the final structure and properties.

The potential impact of organizational defects caused by improper key control parameters during the process stage on the service performance of lining plates

1. Heating and insulation temperature: usually 1050 ℃ -1100 ℃

Time: determined based on the thickness of the section, ensuring that the through burning temperature is too low or the time is insufficient: carbides are not fully dissolved, and residual network or granular carbides remain.

Excessive temperature: The grain size may be coarse, and even overheating cracks may occur. Reduced toughness: Residual carbides become the source of cracks, significantly reducing the impact energy (ak value) and making early brittle fracture more likely to occur.

Weakening of comprehensive performance: Coarse grains reduce the strength and plasticity of the material.

2. Quenching transfer time: The time interval from furnace discharge to water injection is too long. During the air cooling process, austenite precipitates carbides and forms a thin film along the grain boundaries. Causing "quenching brittleness": severely damaging toughness, making it possible for the lining plate to crack during installation or initial impact, and weakening the work hardening ability.

3. Water quenching cooling rate and water temperature: Sufficient cooling rate must be ensured, usually the water temperature should be below 40 ℃. Insufficient cooling (such as small water tank capacity, high water temperature, and insufficient stirring) cannot suppress carbide precipitation and obtain non-uniform austenite structure. Insufficient hardening potential: The surface hardness improvement is limited, and the wear resistance cannot meet expectations, manifested as abnormally rapid wear.

4. Subsequent processing usually involves incorrect tempering without tempering: tempering in the brittle zone at 250-400 ℃ leads to the re precipitation of carbides. Loss of toughness: The material becomes brittle, completely losing the impact resistance characteristics that high manganese steel should have.

3、 From process execution to performance validation

A standardized water toughening treatment should be able to verify its effectiveness through the following tests:

Hardness testing: The overall Brinell hardness after processing should be within the typical range of HB170-220. Too high may indicate rapid cooling or other phase transitions, while too low indicates insufficient solid solution.

Metallographic structure inspection: Under a microscope, the qualified structure should be a single austenite grain, with clear and clean grain boundaries, and no continuous network or large block carbides. This is the direct basis for determining the success of water toughening treatment.

Impact performance testing: Sampling is conducted for Charpy impact testing, and the ak value should meet the material standard requirements (such as Mn13, which usually requires ≥ 150J/cm ²). This is a key quantitative indicator for measuring resilience.

4、 Tips for user selection and evaluation

Given the decisive role of water toughening treatment, users can adopt the following practical strategies when purchasing high manganese steel liners:

Pay attention to the heat treatment capabilities of suppliers: understand whether they have temperature controlled heating furnaces, sufficient quenching water tanks (capacity, circulating cooling and stirring systems), and standardized process discipline.

Request for quality certification documents: In addition to the material list, suppliers can be requested to provide metallographic structure photos and heat treatment process curve records of products from the same batch as indirect evidence of process control.

Conduct random inspection upon arrival: Conduct hardness testing on the new lining board (avoiding areas with extremely high or low values), and ensure that the hardness values are within a reasonable range and relatively uniform.

Establish quality traceability: Record batches of lining plates with stable performance or early failure, and conduct third-party failure analysis (including metallographic examination) if necessary, using the results as an important basis for supplier evaluation.